I have had two defecography test and have never heard of a bladder catheter. That being said, it doesn't mean he doesn't have a good reason for it. Ask what purpose the cathater serves. He may want to see if the bladder is moving when the pelvic floor muscles are used. Never be afraid to ask questions. Too many questions are not enough.

yes I've had defecography, but without bladder test. What david says makes sense though... bladder movement could cause bowel/pouch changes.
And yes. ASK. do not be afraid. This is YOUR body.
good luck

Thanks for your response, guys. I thought this was odd when he told me about it from what I have heard on this site before. I think he is just trying to be thorough in his testing because if he can't figure out what is wrong, I have to go to Cleveland Clinic in April. I really don't want to make the trip, so I appreciate his effort.

Dr. Strong at the Cleveland Clinic is who treated me. I was there for three weeks after I had my first j-pouch removed and a second one created. Believe me it is worth the trip. I traveled from NC to Cleveland. Good luck!